foreword

The conventional dewatering process for coal slurry in coal preparation plants is to use ordinaryfilter pressThe solid-liquid separation is achieved by the pressure of the pressurised pump. Due to the limitation of the power of the ordinary filter press by the pressurised pump, there are always the problems of slow pressurisation speed, low dewatering efficiency, high cake moisture and high energy consumption. Therefore, out of the ordinary filter press box, try a new, efficient coal slurry dewatering process is currently one of the coal industry urgently need to solve the problem.

Shandong Province Sanhekou Coal Mine Coal Beneficiation Plant has successfully carried out a coal processing plant with a small-scaleRapid filter pressesThe process practice of coal slurry dewatering is of great practical significance for reducing investment and energy consumption. Sanhekou Mine Coal Processing Plant is a coking coal processing plant with an annual washing capacity of 200,000t. The original design of coal slurry water is to pass through the slurry sedimentation pond and recover the slurry by natural sedimentation, which seriously affects the continuity of production. Therefore, in order to reduce the concentration of washing water, reduce environmental pollution, and increase production, it is necessary to build a filter press plant. After investigation and demonstration and comparison of several programmes, decided to try a small rapid filter press for coal slurry dewatering, according to the parameters provided by the mine need to use XMZG100/1000 type, and this filter press at that time has not been tested successfully, after consultation with the manufacturer decided to first in the 603 back to the wind lane of the mining airspace area of each confinement wall top and bottom and the two gangs of the coal and rock body of the rock door closed between the walls of the spraying of Marisan, after repeated observations, the sealing is good, all over the wind, and the airflow is good, and the air flow is good. After many observations, the sealing is good, the air volume is significantly reduced than before spraying, compared with the previous common wall grouting closure method, there is no gas over-limit phenomenon in front of the closed wall of the stone door, the oxygen concentration in the closed wall has also dropped from 15% to 1%; 605 working face, the gas temperature in the void area has dropped from 30 to 22T, and the gas temperature has dropped from 8.5% to 0.5% and stabilised, ensuring that the 601 working face will be able to provide the most suitable working environment for the workers. The gas temperature of 605 working face has been reduced from 30 to 22T, and the gas has been reduced from 8.5% to below 0.5% and stabilised, which ensured the safe mining of 601 working face and achieved good economic and social benefits.

8 Benefits analysis

The use of Malisan filling to reinforce the coal rock body at the top and bottom of the confining wall and the two gangs of the mining hollow area has outstanding comprehensive benefits.

It improves the stability of surrounding rock. Malisan contains resin and catalyst two components, injected into the coal rock layer where seconds, the chemical reaction generated by the polyester product expansion, the peripheral rock loosening circle fissures to be filled, the broken loose thumping stone bonding, so that the peripheral rock to form a whole structure, improve the stability of the peripheral rock and the compressive load-bearing capacity. After two months of construction, there is no obvious deformation and fragmentation, and the phenomenon of gas overflow has been controlled. Successfully cured the air leakage phenomenon from the confinement to the mining area, eradicated the hidden danger of gas overloading in the mining area, and ensured the safe production of the mine.

Ensure the safety of construction workers. The top and bottom plates of the confining wall and the coal and rock bodies of the two gangs in the mining area are extremely threatened by gas overload. The injection of Marisan ensures the normal safe production of the coal mine.

Reduced labour intensity. The conventional way to deal with the gas overflow from the top and bottom plates of the confining wall and the two gangs of the mining area is spraying concrete, injecting yellow slurry and other methods, which have a large amount of workload and a poor construction environment. Instead, we adopt Marisan injection to reinforce the wall, and try to produce one machine at the time of construction, and try it in our mine. Practice has proved that the choice of this programme is correct, and all the indexes have reached the design requirements, achieving the clean water coal washing.

2Feasibility test of filter press using high pressure wind as power source for coal slurry dewatering

Coal beneficiation industry with filter press has a history of more than 20 years, but are using pressurised pumps as a power source, and are large-size, with high-pressure wind as a power source of small machines are still in the experimental stage, the advantages and disadvantages of the two are mainly manifested in:

The minimum filtration area of the original filter press is 340 square metres, the supporting facilities are also larger, and the dewatering function is single, relying solely on the pressure of the feed pump to dewater, the filter press takes a long time, and the cake is high in moisture, which is not suitable for the use of small-scale coal washing plant.

Small rapid filter press circulates fast, dewatering effect is good, the reference to high-pressure wind and can save equipment investment, reduce power consumption, economic benefits are considerable.

3 Filter press and auxiliary equipment selection

According to the production needs, my mine tried XMZG100/1000 type chamber filter press. This model was originally used in chemical industry, light operation is convenient, low labour intensity. Accelerated construction speed. Malisan has quick reaction and short hardening time, which ensures the quickness of filling and reinforcing work, and it can be used for "first aid" treatment of hidden dangers without affecting other construction tasks. To deal with the wind leakage problem of the airmoving area, we have to analyse the specific situation, and we can't just use the traditional method. Otherwise, potential safety hazards will always exist. The traditional methods such as system adjustment and slurry plugging are only suitable for dealing with general air leakage problems of the closure wall, and the effect is not ideal for the roadway which will be affected by the pro-active pressure. The application of pressure injection marisan technology to fill the coal and rock bodies on the top and bottom plates of the confining wall and the two gangs not only improves the pressure resistance and stability of the top and bottom plates of the confining wall and the coal and rock bodies on the two gangs, but also blocks the air leakage channels of the air-mining area, which can fundamentally meet the requirements of curing the root cause of the problem.

Main disadvantages. The use of Malisan construction, unit production costs increase; Malisan catalyst raw materials containing slightly corrosive chemicals on the skin, the construction personnel need to wear protective equipment when operating.

reach a verdict

The application of Malisan slurry injection technology in confinement has proved that the injected slurry expands and penetrates in the fissure, and gels the broken bang stone, which not only improves the stability of the confinement wall, but also effectively fills the fissure of the peripheral rock of the confinement wall, and strengthens the national rock of the roadway, and prevents the leakage of the gas in the air mining area. After the fissure filling, the gas concentration around and near the closure wall is reduced to below 0.5%, which ensures the safety of the mine, and because of the simple construction process, it is a kind of safe and efficient chemical filling method, which has achieved good technical and economic benefits, and the comprehensive social benefits are obvious, although the unit cost has increased.

(Received: 2010-7-23) industry and other industries, is the first filter press manufactured according to the design requirements of my mine using mine high pressure wind as a power source for coal slurry dewatering. Its main technical features are shown in the table, XMZG100/1000 filter press main technical features.

Since the production of filter press requires the wind pressure less than 0.8MPa and the air volume is determined according to the production capacity, and the high-pressure wind pressure of the mine meets this requirement, and since the air volume is small, there is enough spare capacity for the filter press to be used, therefore, only a wind pipeline needs to be set up, and no other wind supply equipment is required. The material tank is a specially designed pressure tank, which is determined according to the volume of the filter chamber of the filter press and the concentration of the feeding material.

The whole process of filter dewatering process involved in the valve control is more, and requires the realisation of programmed automation, so the valve selected pneumatic valves and solenoid valves of two kinds.

Table 1 XMZG100/1000 filter press main technical features
serial number	name (of a thing)	unit (of measure)	numerical value
1	Filter press area	m2	100
2	Filter plate size	nun	1000×1000
3	Number of filter plates.	lump (of earth)	50
4	Number of chambers	classifier for individual things or people, general, catch-all classifier	51
5	Chamber thickness	mm	42
6	Filter chamber volume	m3	1.9
7	Chamber Pressure	MPa	0.6-0.8
8	pressing pressure	MPa	0.6-0.8
9	Oil nail pressure	MPa	7-14
10	Motor power	kW	5.5
11	Overall Dimension(LXWXH)	m	6.7 x 1.5 x L3
12	Weight		24880

4 Improvement of rapid filter presses

4.1 Improvement of defective rapid filter presses

In view of the problem that it is difficult to dislodge the filter cake due to the adhesion of the cake to the ordinary filter plate, we replace all the filter plates with the press plate with rubber diaphragm. After the transformation, the shedding effect is better, after the action of the filter plate, the filter cake will fall off by itself.

Change to use higher strength nylon silk textile filter cloth. The thickness of this filter cloth is comparable with the original filter cloth, but its high compressive strength, the use of a number of cycles, up to 3,000 cycles, while high-strength nylon prevention and control of filter cloth filtration speed, the advantages of good effect of cake shedding.

Improve the assembly form of high-strength nylon textile filter cloth, press the filter cloth directly with the rubber diaphragm, to prevent and control the rapid damage of the filter cloth in the centre feeding hole, and save the cost.

5 Determination of filter press process parameters

5.1 Determination of air pressure and air consumption

Generally, the pressure of high pressure wind in mine is 0.6MPa, which is suitable for the ventilation of coal mine production. In the filter press process, only the slurry feed and pressing time need to use high pressure air, a single cycle of air time is not more than 5min, air consumption in 8m³/The effect on mine ventilation is negligible.

5.2 Determination of single cycle working time

Single-cycle working time formula: T=t,+t₂+t₃+t4+t5+t6

Eq. Filter plate top tightening time;

t2 - Inlet slurry pressure filtration time;

t₃-Press dewatering time;

U-Blow time;

-Filter press release time;

G - Unloading time.

Which is a constant, respectively, lmin, 50s, 2.5min. Therefore, a reasonable choice of t "3, t4, is to reduce the single-cycle working time, the key to improve production efficiency.

Slurry time t2: the role of the slurry is to make the slurry solid-liquid separation, by the subsequent press dewatering, slurry speed with the increase in the thickness of the cake and decreased, so when the filter chamber is full of gastric material out of the liquid mouth liquid flow was broken column state, stop the slurry. Determined in the average feed concentration of 150g / l, wind pressure of 6MPa, into the pulp time is generally 3~5min₀

Pressing time shall be pressed to make the moisture of filter cake drop 3%~5%, when pressed to a certain limit, and then extend the pressing time, the product moisture content does not change much. The time is generally considered to be 30~60s.

Blowing time plate: 30s, subject to the emptying of the residual gas in the material tank.

Therefore, the single cycle working time is between 8 and 12 min.

5.3 Determination of the amount of coal slurry to be treated

There are 51 chambers in the filter press, after a lot of measurements show that each piece of filter cake weighs about 41.7kg, the total weight of the filter cake in a single cycle is 2.13t, which is equivalent to the dry coal sludge processing capacity of a single cycle of 1.55t. Calculated by 10min for one cycle, the filter press can process 9.3t of coal sludge in one hour, which can satisfy the needs of the production of my mine.

Trial results

After the whole process system was formally put into production operation, it achieved better process indicators and reached the expected purpose. Compared with the traditional design programme, the effect is remarkable. Because of the selection of models and supporting facilities miniaturisation, supporting the relative reduction in the floor space of the workshop, a one-time savings in equipment and infrastructure investment of 604,400 yuan. Supporting motor power reduction, the reference to high-pressure wind, the opening of the pump time is reduced by half, the annual power savings of 322573.5 degrees, saving 161268.75 yuan. The moisture of the product has been reduced to about 20%, realising clean water coal washing, improving the recovery rate of fine coal and the quality of fine coal, which brings considerable economic benefits. The whole process of filter press realises automatic control, and the operation and adjustment are convenient and reliable.

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